Conventionally, the type of cards used as bank CD cards, cards for presale of train passenger tickets, and the like, are constructed by the application of magnetic tape to a paper or plastic plate. This magnetic tape section has the capability of storing account numbers, cash balances, and the like. However, the storage volume of the magnetic tape is extremely small and there is just enough room to store a few columns of numbers and symbols.
In addition, the details stored on this tape cannot be rewritten at will.
It is the so-called IC card that is a card having an integrated circuit to store electrically rewritable ROM (EEPROM) so as to overcome the problems as mentioned above.
Specifically, the IC card was developed with the object of increasing the storage volume, and consideration was given to the use of an integrated circuit providing a large memory volume to make rewrite possible. However, use of terminal equipment connected to a host computer is required not only for the total memory possible within such a card but also for even the smallest amount of data which the cardholder wishes to know, and the data must first be displayed on the display device of the terminal equipment to read the details.
For this reason, there has been a demand for a card which has the capability of displaying the stored data content so that it can be made to appear on the card itself.
For this reason, it is necessary that the part which performs the display and the part that stores the data be formed on the same card.
A liquid crystal display is most generally used as the part for performing the display because of its display capabilities and low electric power consumption and the like.
On the other hand, an EEPROM (Electrically Erasable Programmable ROM) is generally used as the part which stores the data, because of its large storage content and the like.
However, forming them on the same card would increase the number of processes to cause the card structure to become complicated, and many other technical problems would be produced.
The inventor of the present invention has invented "an optical disk device using ferroelectric liquid crystals" for which application has been made for a patent (Japanese Patent Application Sho-60-130190). This is a storage (memory) using ferroelectric liquid crystals. The reading, rewriting, and erasure of the stored data is handled in the same way.
When an optical disk memory using the ferroelectric liquid crystals is applied in practice, there are a number of problems which must be overcome.
Examples of such problems are as follows.
(1) Between the disks, the molecules must be correctly lined up and a monodomain formed in a region corresponding to at least one bit. PA1 (2) A storage region must be established on the disk. Specifically, adjacent individual storage regions must be properly isolated, and any case of erroneous access must be detected.